At Anonymous the news was taken equally well, and while the @AnonymousIRC Twitter account tried to recruit other organisations such as Wikipedia and Google into joining the protest it received tweets of support for its plans from its members.

The Reddit announcement has also caused Wikipedia's Jimmy Wales to have another think about whether it is right to turn off his web site in protest, a tactic that was mooted last year.

"Reddit recently announced that they will be blacking out the site from 0800-2000, Jan 18th," he said in a statement on his personal page on the web site. "Were Wikipedia to consider a similar measure, it might make sense to do so at the same time, to increase impact."

Wordpress is also joining the protest and has posted a strong call to arms on its website. "You are an agent of change. Has anyone ever told you that? Well, I just did, and I meant it," it says. "There's something going on in U.S. politics right now that we need to make sure you know about and understand, because it affects us all."

That something is SOPA, and Wordpress said that if it is left unchecked and unprotested it will have a terrible impact on the internet and the web sites that depend upon it.

"We are not a small group. More than 60 million people use WordPress - it's said to power about 15 per cent of the web. We can make an impact, and you can be an agent of change," it said as it called on its users to protest.

"The Senate votes in two weeks, and we need to help at least 41 more senators see reason before then. Please. Make your voice heard." µ